CN1212687C - Multilayer stacked electrochemical cell and method for preparing same - Google Patents

Abstract

The present invention relates to an electrochemical element, specifically an electrochemical element with improved energy density comprising stacked electrochemical cells. In order to achieve such objects, the present invention provides an electrochemical element comprising electrochemical cells which are multiply stacked, said electrochemical cells formed by stacking full cells or bicells having a cathode, a separator layer, and an anode sequentially as a basic unit, and a separator film interposed between each stacked cell wherein, said separator film has a unit length which is determined to wrap the electrochemical cells, and folds outward every unit length to fold each electrochemical cell in a Z-shape starting from the electrochemical cell of a first spot to the electrochemical cell of the last spot continuously while the remaining separator film wraps an outer portion of the stacked cell and a method for manufacturing the same.

Description

Multilayer stacked electrochemical cell and preparation method thereof

Background of the invention

(a) Field of Invention

The present invention relates to an electrochemical element and a preparation method thereof, in particular to an electrochemical element comprising multilayer stacked electrochemical cells and a preparation method thereof with improved energy density.

(b) Related technical description

There is growing interest in energy storage technologies. With the recent addition of electric carriers to portable phones, camcorders and notebook computers, the field of application of storage batteries has been extended to this series of products. This expansion has led to increased research and development work on secondary batteries with appreciable output. In this regard, the study of electrochemical elements is one of the areas that has attracted much attention, of which rechargeable batteries are of most interest. Recent development work has gone into designing new batteries and electrodes to increase capacity and specific energy.

Among the secondary batteries that have been used, lithium-ion batteries developed in the 1990s are gaining popularity because of their higher operating voltage compared to Ni-MH, Ni-Cd, and sulfuric acid-lead batteries using aqueous electrolytes and energy density. However, these lithium ion batteries have safety problems due to the use of organic electrolytes which make the batteries flammable and explosive. Also, lithium ions have the disadvantage of being difficult to manufacture and process. Recent lithium-ion polymer batteries overcome these disadvantages of lithium-ion batteries and are expected to become next-generation batteries. However, these lithium-ion polymer secondary batteries have considerably lower capacity compared with lithium-ion secondary batteries, and have particularly insufficient discharge capacity at low temperatures; therefore, there is a need for improvement thereof.

The capacity of the storage battery is proportional to the amount of electrode active material. Thus, it will be particularly important to design a battery structure that can pack as much electrode material as possible into the limited space within the battery pack. The most widely known and used type of battery structure is the jelly-roll structure, which is used for cylindrical or prismatic batteries. Such a structure is prepared by coating and rolling the electrode active material onto a metal foil serving as a current collector, cutting it into strips with a predetermined width and length, and separating the cathode and anode with a separator. Divide and roll it into a spiral. Such a jelly-roll structure is widely used in the manufacture of cylindrical batteries. However, the structure has a small radius of curvature at the central portion of the spiral, which often causes a large stress on the curved surface of the electrode, thereby often causing the electrode to come off. This promotes the deposition of lithium metal in the central portion of the electrode during repeated charging and discharging of the battery, which shortens the life of the battery and reduces the safety of the battery.

In general, the well known and used method of making thin prismatic batteries consists of rolling a spiral jam roll into an oval as described above and compressing the oval before inserting it into a rectangular container. This method does not overcome the aforementioned problems of reduced life and safety, but instead has a more serious problem caused by a reduced radius of curvature due to the ellipse. And performance degradation is even more of a problem, since making a tight helical structure is inherently impossible. In addition, the discrepancy between the oval shape of the jam roll and the rectangular shape of the container reduces the proportion of available volume. This is known to reduce gravimetric energy density by about 20% and volumetric energy density by 25% when the container is taken into account. In fact, prismatic Li-ion batteries have been reported to have lower capacity density and specific energy compared to cylindrical batteries.

Recently, various patents and technologies have been disclosed which propose a solution to the problem of the spiral-shaped jam-roll type structure and provide a battery structure suitable for a prismatic container. However, these proposals only partially solve the above-mentioned problems, or cause other more difficult problems to overcome, so they are not practical solutions. For example, U.S.P No. 5,552,239 discloses a method of first placing and laminating a separator or polymer electrolyte between the cathode and anode, cutting it into a strip shape with a predetermined length and width, and then gradually folding it into A square battery with a cathode/separator/anode stack structure. The inventors of the present invention tried to repeat this method, but found it difficult to manufacture a battery so used. The laminated cell is so stiff that it is difficult to fold, and when an external force is applied to cause it to fold, problems arise in the fold area because the cell, like a jelly-roll cell, is fragile.

In the fan-folding method disclosed in U.S.P.No. 5,300,373, the pressure and stress of the inner layer at the abruptly folded portion is transferred to the outer layer and dispersed so that twisting and stretching occurs, resulting in a "dog bone" shaped battery . Thus, the problems of detachment, cracking, crumbling, or snapping encountered in jam-roll structures still occur frequently. Also, batteries of this construction are inherently prone to breakage; therefore, the possibility of making a practically usable battery is very low.

Meanwhile, U.S.P. No. 5,498,489 attempted to solve and improve this type of problem in the folding section. This patent provides a basic method to avoid electrode detachment by omitting the electrodes in the folded part and by using only the current collector and separator or polymer electrolyte part for connection. However, there are difficulties in forming such a battery. Also, too many current collectors are used, and the structure wastes too much electrolyte. Therefore, this structure is not very practical because it has many disadvantages.

Summary of the invention

An object of the present invention is to provide a kind of electrochemical element and its preparation method, described electrochemical element comprises the electrochemical cell of multi-layer stack, and wherein compared with prior art, this element is easy to manufacture, and can effectively utilize can The structure of the obtained space.

Another object of the present invention is to provide an electrochemical element and a method for its preparation which maximize the content of active electrode material and which are easy to manufacture.

These and other objects can be achieved by an electrochemical element comprising a multilayer stacked electrochemical cell by stacking as a basic unit a full cell sequentially having a cathode, a separator, and an anode, and placing The separator between each stacked full cell is formed, wherein:

The separator has a unit length capable of enveloping the electrochemical cell and is folded outwards each unit length starting from the electrochemical cell at a first point to fold each electrochemical cell in a Z-shape, continuously until the last point electrochemical cells, while the remaining separator wraps the exterior of the stacked cells.

An electrochemical element according to a preferred embodiment of the present invention, wherein said separator is selected from microporous polyethylene films, microporous polypropylene films, multilayer films prepared by combinations thereof, and polymers used as polymer electrolytes A film, the polymer comprising polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride-hexafluoropropylene copolymer.

In addition, the present invention provides a method for preparing an electrochemical element using a full battery, comprising the steps of:

a) Continuously or alternately place full cells above and below the separator;

b) laminating the full cell placed in step a) and the separator; and

c) Fold the laminated full cells and the separator of step b) outward toward the full cells immediately adjacent to the first full cell, fold each full cell in a Z shape, and roll up the remaining The separator wraps at least one turn around the outside of the stacked full cells, thereby stacking the full cells.

In addition, the present invention provides an electrochemical element comprising a multilayer stacked electrochemical cell, the electrochemical cell is stacked by

i) a bicell having, in sequence, a cathode, a separator, an anode, another separator, and another cathode as the basic unit; or

ii) as a basic unit, a bicell having in sequence an anode, a separator, a cathode, another separator, and another anode;

and a separator placed between each stacked bicell, wherein:

The separator has a unit length capable of enveloping the electrochemical cell and is folded outwards each unit length starting from the electrochemical cell at a first point to fold each electrochemical cell in a Z-shape, continuously until the last point electrochemical cells, while the remaining separator wraps the exterior of the stacked cells.

According to the electrochemical element comprising a multilayer stacked electrochemical cell according to a preferred embodiment of the present invention, wherein the separator is selected from microporous polyethylene film, microporous polypropylene film, multilayer film prepared by combinations thereof, and a polymer film used as a polymer electrolyte, the polymer comprising polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride-hexafluoropropylene copolymer .

Also, the present invention provides a method for preparing an electrochemical element using a double cell, comprising the steps of:

a) Place the double cells continuously or alternately above and below the separator;

b) laminating the double cell placed in step a) and the separator; and

c) Fold the laminated bicell and the separator of step b) outward toward the bicell immediately adjacent to the first bicell, fold each bicell in a Z shape, and roll up the remaining The separator wraps at least one turn around the outside of the stacked bi-cells, thereby stacking the bi-cells.

Brief description of the drawings

Figure 1 shows the layered structure of a full cell including a double-sided coated cathode, anode and separator.

Figure 2 shows a layered structure of a battery in which multiple full cells are stacked and a separator is placed between the stacked cells.

Fig. 3 shows a layered structure of a battery comprising a multi-layer stacked full cell, the outermost electrode of the outermost full cell, coated on one side and metal foil on the other side, a separator placed on between full batteries.

Figure 4a shows a layered structure of a bicell, where the middle layer is the anode and the outer two sides are the cathode.

Figure 4b shows a layered structure of a bicell, where the middle layer is the cathode and the outer sides are the anodes.

Figure 5 shows the layered structure of a battery in which two types of bicells are stacked alternately with a separator interposed between the bicells.

Figure 6 shows a layered structure of a battery, including bicells in which one side of the outermost electrode of the outermost bicell is coated and the other side is a metal foil, and the two types of bicells are stacked alternately with an isolation The membrane is placed between the double cells.

Fig. 7 is a developed view of a battery in which full cells are successively placed on the cut separator and then laminated so that the full cells are precisely aligned in a row for stacking.

Fig. 8 is a graph showing the charge and discharge characteristics of the electrochemical element of the present invention.

Fig. 9 is a developed view of a battery in which full cells are successively placed on the cut separator and then laminated so that the full cells are precisely aligned in a row for stacking.

Fig. 10 is an expanded view of a battery in which bicells are successively placed on the cut separator and then laminated so that the bicells are precisely aligned in a row for stacking.

Fig. 11 shows the cycle characteristics of the electrochemical element of the present invention.

Fig. 12 is an expanded view of a battery in which bicells are placed sequentially on the cut separator and then laminated so that the bicells are precisely aligned in a row for stacking.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the present invention will be discussed in detail with reference to the accompanying drawings.

[Function]

The invention provides a battery structure and a preparation method thereof. Compared with conventional batteries, the battery of the invention is easier to prepare and uses space more effectively. The present invention provides a unique and simple way of maximizing the content of electrode active materials in prismatic batteries while overcoming the various deficiencies of the various conventional battery structures described above. In principle, the present invention does not utilize longitudinally cut electrodes used for spiral rolling or folding, but employs a method of stacking electrodes cut into a predetermined shape.

The electrochemical cell of the present invention is formed by stacking full cells or double cells as basic units.

The full cell of the present invention has a structure in which layered constituents cathode 7, anode 8 and separator 15 are cut into regular shapes and sizes and then stacked as shown in FIG. All electrodes use current collectors 11 and 12 coated with electrode active materials 13 and 14 on both sides. Such a structure is regarded as one unit cell, which is stacked to form a secondary battery. To achieve such a purpose, the electrodes and the separator must be fixed to each other. For example, in a lithium rechargeable battery, the main component of the cathode material 14 is a lithium intercalation material, such as lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, or a composite oxide formed by a combination of the above oxides, the cathode The material forms cathode 8 by coating cathode current collector 12, which is a metal foil made of aluminum, nickel, or a combination thereof. The main component of the anode material 13 is lithium metal or lithium alloy, and lithium intercalation materials, such as carbon, petroleum coke, activated carbon, graphite, or other carbons, and the anode material 13 is coated on the anode current collector 11 to form the anode 7, the collector Appliance 11 is a metal foil made of copper, gold, nickel, copper alloys, or combinations thereof.

The isolation layer 15 includes a microporous polyethylene film, a microporous polypropylene film, or a multilayer film prepared by a combination thereof, or a polymer film used as a solid polymer electrolyte or a gel-type polymer electrolyte, such as poly(1, 1-Difluoroethylene), polyethylene oxide, polyacrylonitrile, or poly(1,1-difluoroethylene-hexafluoropropylene) copolymer. In addition, using a second gel polymerization method disclosed in Korean Patent Application No. 99-57312 comprising a first microporous polymer layer and poly(1,1-vinylidene fluoride-monofluorotrichloroethylene) copolymer Layered, polymer membranes used as polymer electrolytes are also very effective. An important feature that the separator 15 needs to have is a lamination bonding property to constitute a unit cell, which is a kind of full cell.

The unit structure of the full cell 17 shown in FIG. 1 is sequentially composed of a cathode, a separator and an anode. The separation layer 15 is naturally located in the center of the cell. A plurality of such unit cells can be stacked according to the required number to complete a storage battery with a practical capacity. For example, Figure 2 shows 5 full cells stacked in succession. As for the isolation layer 15, as mentioned above, the insertion mode of the polymer isolation layer, or the polymer isolation membrane with micropores used as the polymer electrolyte is particularly important, and FIG. 2 shows one mode provided by the present invention.

The full cells 17 of the present invention are stacked one after the other by folding the longitudinally cut separator 19 in a Z-shape starting from one full cell. Such a structure is a very efficient structure because the outside active coating material that is not used in one unit cell is shared with the active coating material of the opposite electrode of the adjacent another unit cell. The separator 19 is terminated by fixing tape 27 after the folding has been completed and around the full cell. In addition, in addition to tape, it can also be terminated by hot-melt method. That is, the separator itself is fixed and bonded together by heat sealing, which is performed by bringing a heat sealer, hot plate, etc. into contact with the separator. The number of stacked full cells can be determined according to the required capacity of the final storage battery.

In the present invention, the structure 44 of FIG. 2 has another meaning. According to the experience of the present inventors, the surface between a separator, such as a thin film used as a polymer electrolyte membrane, or a polymer separator, and an electrode is important. When the battery is actually used after being injected with a liquid electrolyte and packaged, the battery will go through many charge and discharge cycles. When the contact of the surfaces cannot be maintained constantly and becomes unstable, the performance of the battery will drop sharply and the actual capacity of the battery will decrease. Depending on the structure of the accumulator, this consequence may be manifested from the start, or it may be revealed over time. Therefore, pressure needs to be applied to keep the surface constant. The present invention provides a new battery structure and its assembly method as a means of maintaining pressure while substantially solving the above-mentioned problems. In this context, Figure 2 has another meaning.

As can be seen in the structure 44 of FIG. 2 , the method of stacking the full cells as unit cells while folding the separator 19 in a Z shape effectively utilizes the electrodes between the full cells. The pressure created by wrapping around the full cell roll after folding compresses all the cells formed between the polymer film or polymer separator that acts as the polymer electrolyte and the electrodes. The final termination with adhesive tape 27 is a measure to constantly maintain such a pressure that keeps the surfaces in stable and constant contact.

For the separator 15 and the separator 19, a polymer separator of a different material or the same material or a polymer film used as a polymer electrolyte may be used. The separator 15 must have lamination bonding properties to constitute a full cell unit cell, but the separator 19 does not need to have such properties because the full cell 17 can be assembled by folding the separator 19 . However, for another type of assembly using a cell structure as shown in structure 44 of FIG. 2, it is preferred to use a separator 19 having adhesive properties. In this regard, it is most suitable to use as the separator 19 of the accumulator battery of the present invention a polymer film that is used as a polymer electrolyte, the polymer film comprising a first microporous polymer layer, and poly(1,1-vinylidene fluoride - a second gel polymer layer of chlorotrifluoroethylene) copolymer. The method of assembly of the structure 44 of FIG. 2 can vary widely when a novel polymer film is used as the isolation membrane 19 . That is, there are two possible orientations of each full cell 17 when bonded to the separator 19, an upper orientation and an inferior orientation. If there are 5 full batteries as shown in Figure 2, there can be 25 assembly ways. In this method, after the separator 19 is unfolded longitudinally, the full cell can be arranged on or under the separator 19 in any of 25 ways, then laminated, followed by simple Z-folding, and rolled. a week. The advantage of this method is that the design and layout of the assembly process is easy.

The structure 45 shown in FIG. 3 eliminates the useless outermost active electrode material of the structure 44 of FIG. 2, such that the structure has maximum space efficiency. When one of the electrodes is coated on both sides and the full cell structure in which the other electrode is coated on one side is defined as another full cell 17', the structure 45 of Fig. 3 adopts such a full cell 17', so that the structure of Fig. 2 The only remaining useless outermost active electrode material shown in structure 44 is the metal foil. The result is a further reduction in thickness without loss of capacity, resulting in a further increase in space efficiency. However, when the number of stacked cells increases, there is not much difference in space utilization compared with the structure 44 of FIG. 2 . However, the structure 45 of Fig. 3 is effective in the recently discussed very thin card-type storage battery.

In the present invention, when a plurality of double cells are stacked as a unit cell, in the same manner as the above method, a space-efficient cell structure is employed. To achieve such purpose, two types of bicells 23 and 24 are defined as shown in Fig. 4a and Fig. 4b respectively, both of which use electrodes coated on both sides. The anode of the bi-cell 23 is placed in the middle, and the cathode is placed on both sides of the outer side, while the cathode of the bi-cell 24 is placed in the middle, and the anode is placed on both sides of the outer side. Active electrode materials and polymer separators or polymer films used as polymer electrolytes such as separator 15 that can be used are the same in detail as discussed above for full cells.

Structure 46 of FIG. 5 shows one way of building a battery using two types of bicells as basic unit cells. When the double cells 23 and 24 are alternately stacked, and the aforementioned polymer separator, or the separator 19, such as a polymer film used as a polymer electrolyte is inserted between the double cells in a Z-folded manner, in a double cell The useless outer active coating material in the middle is naturally shared with the opposite polarity of the adjacent other bicell to form a new full cell, which is a very efficient structure. As can be seen in structure 46 of FIG. 5, if separators 19 are placed continuously between the cells, and the bi-cells are stacked alternately, the polarity of the battery is formed naturally without conflict. The double cells stacked on the outermost side of the storage battery can be the double cells 23 or 24, the only difference being that the useless electrode material is an anode or a cathode. As the number of stacks increases, the proportion of such useless electrodes decreases and it has only a small effect on the actual thickness of the electrodes. In other structures 46, the manner and structure of inserting the separator 19 are the same as those of the full cell in every detail, and in this structure, the functions of the separator 19 and the adhesive tape 27 are also the same.

The structure 47 shown in FIG. 6 omits the outermost active electrode material of the structure 46 of FIG. 5 so that the structure has the greatest space efficiency. When the substrate (') (primes (')) is used to represent the structure in which only one of the two outer electrodes of the double cell is left with a metal foil, as shown in the structure 47 of FIG. 6, the double cell 23' As the structure of stacking the outermost double cells of the storage battery (regardless of whether the outermost double cell is the double cell 23' or the double cell 24'), only the metal foil is left on the useless part of the outermost active electrode material, so that the thickness is further increased. reduced without loss of space efficiency. This makes its advantages directly related to space efficiency. When the number of stacked double cell layers increases, the space efficiency is not much different from that of the structure 46 of FIG. 5 . However, in the thin-layer card-type storage battery, the structure 47 of the stacked battery of FIG. 6 is effective.

For prismatic batteries, the battery structure provided by the present invention is very efficient. Typically, a liquid electrolyte is injected at the time of packaging. For such purposes, aluminum prismatic cans or aluminum laminated sheets are used as containers. The liquid electrolyte is an A ⁺ B ^- salt dissolved or dissociated in an organic solvent, wherein A ⁺ includes an alkali metal cation, such as Li ⁺ , Na ⁺ or K ⁺ , or a combination thereof, and ^B- includes an anion PF ₆ ^- , BF ₄ ^- , Cl ^- , Br ^- , I ^- , ClO ₄ ^- , ASF ₆ ^- , CH ₃ CO ₂ ^- , CF ₃ SO ₃ ^- , N(CF ₃ SO ₂ ) ₂ ^- , C(CF ₂ SO ₂ ) ₃ ^- , or a combination thereof, organic solvents include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), di Methyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), or gamma-butyrolactone , or a combination thereof. Unlike the jelly rolls of a lithium ion battery, the shape of the formation of the battery of the present invention conforms to the shape of the quadrilateral container so that there is no unused space within the container. Therefore, the energy density of batteries can be greatly enhanced to realize highly integrated batteries with maximum active material space efficiency.

The electrochemical element of the present invention can also be applied to various fields except lithium secondary batteries, such as advanced capacitor (supercapacitor), supercapacitor (ultracapacitor), primary battery, secondary battery, fuel cell, sensor, electrolytic device, electrochemical Reactor, etc.

The present invention will be described in more detail below with reference to examples. However, these examples are not to be construed as limiting the scope of the invention in any way.

[Example]

Example 1

Fabrication of stacked cells in which the full cell is the basic unit

(preparation of cathode)

LiCoO ₂ :carbon black:PVDF (polyvinylidene fluoride) at a weight ratio of 95:2.5:2.5 was dispersed in NMP to prepare a slurry, which was then coated on an aluminum foil. After fully drying at 130°C, it was rolled and flattened to prepare a cathode.

A cathode for a full cell was prepared by coating the slurry onto both sides of an aluminum foil. That is, the cathode material on the cathode is coated on both sides of the aluminum cathode current collector. The thickness of the cathode coated on both sides was 140 μm.

(preparation of anode)

Graphite:acetylene black:PVDF at a weight ratio of 93:1:6 was dispersed in NMP to prepare a slurry, which was then coated on a copper foil. After fully drying at 130°C, the anode was rolled and flattened to prepare the anode.

Anodes for full cells were prepared by coating the slurry on both sides of copper foil. That is, the anode material on the anode is coated on both sides of the copper anode current collector. The thickness of the anode coated on both sides was 135 μm.

(preparation of separation layer; separation membrane; polymer membrane used as polymer electrolyte)

Prepare a kind of multi-layer polymer film, wherein has microporous structure, the polypropylene film thickness of 16 μ m is the first polymer isolation layer, poly(1,1-difluoroethylene-chlorotrifluoroethylene) copolymer 32008 ( Solvay) is the second gel polymer layer. 6g of 32008 was added to 194g of acetone and stirred at 50°C. After 1 hour, the fully dissolved clear 32008 solution was coated onto the first polymer release layer made of polypropylene by dip coating method. The coating thickness of 32008 was 1 μm, and the thickness of the final multilayer polymer film was 18 μm. Here, the same material is used for the isolation layer and the isolation film.

(preparation of full battery)

The negative electrode coated with cathode material on both sides of the cathode current collector is cut into a rectangle with a size of 2.9cm × 4.3cm except for the area forming the tab (the area forming the tab should not be coated with electrode material), and the anode material is coated The anode cloth on both sides of the anode current collector is cut into a rectangle with a size of 3.0cm×4.4cm except for the area where the tongue is formed (the area where the tongue is formed should not be coated with electrode material), and the multilayer prepared by the above method The polymer film is cut into a size of 3.1cm×4.5cm, the film is placed between the anode and the cathode, and it is passed through a 100°C roller compactor, and the electrodes and the separator are laminated together to prepare Seven full batteries 17 in Fig. 1 are produced.

(stacked full cells)

After longitudinally cutting the polymer film 19 prepared as above for the polymer electrolyte, as shown in FIG. 7 a , seven full cells were alternately placed on and under the separator 19 . Figure 7b is a side view of Figure 7a. The gap between cells is equal but sufficient to allow the cells to be stacked and separated in a Z-shape with a separator. The polarity of the tabs is arranged as shown in Figures 7a and 7b so that it matches the polarity of the adjacent full cell. That is, the orientation of the electrodes of the first full cell placed above and below the separator 19 is placed in the order of the cathode and then the anode, while the orientations of the electrodes of the second full cell and the next full cell are in the order of In reverse order, place alternately under and above the separator.

The polymer film 19 on which the full cells are placed is passed through a roll laminator so that the full cells are bonded on and under the polymer film 19 .

The full cell 17 bonded at the first point is folded into a Z shape. After the folding is complete, the remaining separator 19 is wrapped around the outside of the stacked full cells and tightly fixed and protected with adhesive tape 27 .

(preparation of battery)

The full cell stacked accumulator prepared as above was placed in an aluminum foil package. A liquid electrolyte comprising 1M _LiPF6 in EC/EMC (1:2 by weight) solution was then injected and packaged.

(evaluate)

The evaluation results of the cycle characteristics of the storage battery using charge and discharge tests are shown in FIG. 8 . Reference numeral 102 shows the cycle characteristics of the prepared secondary battery in which the charge and discharge capacity was 0.2C.

Example 2

Fabrication of stacked cells in which the full cell is the basic unit

(preparation of cathode)

Each cathode was prepared in the same manner as in Example 1 above.

(preparation of anode)

Each anode was prepared in the same manner as in Example 1 above.

(preparation of separation layer; separation membrane; polymer membrane used as polymer electrolyte)

In the same manner as in Example 1, each separator, and a separator for a polymer membrane serving as a polymer electrolyte were prepared.

(preparation of full battery)

As in Example 1, the electrodes and the separator were passed through a roller compactor at 100° C. to be laminated together to prepare eight full cells 17 of FIG. 1 .

(stacked full cells)

After longitudinally cutting the polymer film 19 prepared as above for the polymer electrolyte, 8 full cells were placed on or under the separator 19 as shown in FIG. 9 a . Figure 9b is a side view of Figure 9a. The gaps between the individual cells are equal but sufficient to allow the cells to be stacked and separated in a Z-shape with a separator, where the distance is the sum of the width and thickness of the full cell. The polarity of the tabs is arranged as shown in Figures 9a and 9b so that it matches the polarity of the adjacent full cell. That is, the orientation of the electrodes of the first full cell placed above and below the separator 19 is similarly placed in the order of the cathode and then the anode, while the orientations of the electrodes of the second full cell and the next full cell are Place under and above the separator in reverse order.

The polymer film 19 on which the full cells are placed is passed through a roll laminator so that the full cells are bonded on and under the polymer film 19 .

The full cell 17 bonded at the first point is folded into a Z shape. After the folding is complete, the remaining separator 19 is wrapped around the outside of the stacked full cells and tightly fixed and protected with adhesive tape 27 .

(preparation of battery)

The full cell stacked accumulator prepared as above was placed in an aluminum foil package. A liquid electrolyte comprising 1M _LiPF6 in EC/EMC (1:2 by weight) solution was then injected and packaged.

(evaluate)

The evaluation results of the cycle characteristics of the storage battery using charge and discharge tests are shown in FIG. 8 . Reference numeral 103 shows the cycle characteristics of the prepared secondary battery in which the charge and discharge capacity was 0.2C.

Example 3

Fabrication of stacked cells in which the double cell is the basic unit

(preparation of cathode)

Each cathode was prepared in the same manner as in Example 1 above.

The cathode of the bicell was prepared by coating the slurry on both sides of aluminum foil. That is, the cathode material on the cathode is coated on both sides of the aluminum cathode current collector. The thickness of the cathode coated on both sides was 140 μm.

(preparation of anode)

Each anode was prepared in the same manner as in Example 1 above.

The anode of the bi-cell was prepared by coating the slurry on both sides of copper foil. That is, the anode material on the anode is coated on both sides of the copper anode current collector. The thickness of the anode coated on both sides was 135 μm.

(preparation of separation layer; separation membrane; polymer membrane used as polymer electrolyte)

In the same manner as in Example 1, a separator, a separator, and a polymer membrane used as a polymer electrolyte were prepared.

(preparation of double battery)

The cathode in which the aforementioned cathode material was coated on both sides of the cathode current collector was cut into a rectangle with a size of 2.9 cm×4.3 cm except for the area where the tabs were formed. The anode with the anode material coated on both sides of the anode current collector was cut into a rectangle with a size of 3.0 cm x 4.4 cm except the area where the tabs were formed.

The anode coated on both sides is placed in the middle, and the cathode coated on both sides is placed on the outside of its two sides, and the multilayer polymer film prepared by the above method cut into a size of 3.1 cm × 4.5 cm is placed on each anode and Between the cathodes, pass through a roller compactor at 100° C. to heat-fuse the electrodes and the separator together to prepare four double batteries 23 as shown in FIG. 4 a . The cathode coated on both sides is placed in the middle, and the anode coated on both sides is placed on the outside of its double sides, and the multilayer polymer film prepared by the above method cut into a size of 3.1 cm × 4.5 cm is placed on each anode and Between the cathodes, pass through a roller compactor at 100° C. to laminate the electrodes and separators together to prepare other bibatteries, namely three bibatteries 24 in FIG. 4 b .

(Stacked Dual Batteries)

After longitudinally cutting the polymer film 19 prepared as above for the polymer electrolyte, the 4 bicells 23 and 3 bicells 24 prepared as above were placed on and under the separator 19, respectively. Figure 10b is a side view of Figure 10a. The gap between cells is equal but sufficient to allow the cells to be stacked and separated in a Z-shape with a separator. The polarity of the tabs is arranged as shown in Figures 10a and 10b so that it matches the polarity of the adjacent bicell. That is, the orientation of the electrodes of the first bicell placed on the separator 19 is placed in the order of the cathode and then the anode, while the orientation of the electrodes of the second bicell and the next bicell is in the reverse order , alternately placed below and above the isolation membrane 19.

The polymer film 19 on which the bicells are placed is passed through a roller laminator so that the bicells are bonded on and under the polymer film 19 .

The double cell 23 bonded at the first point is folded into a Z shape. After the folding is complete, the remaining separator 19 is wrapped around the outside of the stacked bicell and tightly fixed and protected with adhesive tape 27 .

(preparation of battery)

The stacked two-cell batteries prepared as above were placed in aluminum foil packaging. A liquid electrolyte comprising 1M _LiPF6 in EC/EMC (1:2 by weight) solution was then injected and packaged.

(evaluate)

The evaluation results of the cycle characteristics of the storage battery using charge and discharge tests are shown in FIG. 11 . Reference numeral 104 shows the cycle characteristics of the prepared storage battery, wherein in the first and second times, the charge and discharge capacity was 0.2C, and then from the third time, charge 0.5C/discharge 1C, and from this time, the result The graph is shown on the curve.

Example 4

Fabrication of stacked cells in which the double cell is the basic unit

(preparation of cathode)

Each cathode was prepared in the same manner as in Example 1 above.

(preparation of anode)

Each anode was prepared in the same manner as in Example 1 above.

(preparation of separation layer; separation membrane; polymer membrane used as polymer electrolyte)

In the same manner as in Example 1, a separator and a separator, ie, a polymer film used as a polymer electrolyte, were prepared.

(preparation of double battery)

As in Example 3, 4 bicells 23 and 4 bicells 24 were prepared.

(Stacked Dual Batteries)

After longitudinally cutting the polymer film 19 used as a polymer electrolyte prepared above, as shown in Figure 12a, 4 double cells 23 and 4 double cells 24 prepared above are placed on the same position of the separator 19, and the double cells 23 are placed on the Above, the double cells 24 are placed below, so that the double cells 23 and the double cells 24 are placed alternately. Figure 12b is a side view of Figure 12a. The gaps between the individual cells are equal but sufficient to allow the cells to be stacked and separated in a Z-shape with separators, where the distance is the sum of the width and thickness of the bi-cells. The polarity of the tabs is arranged as shown in Figures 12a and 12b so that it matches the polarity of the adjacent bicell. That is, the orientation of the electrodes of the first bicell placed above and below the separator 19 is similarly placed in the order of the cathode, then the anode, while the orientation of the electrodes of the second bicell and the next bicell, is In reverse order, under and above the isolation membrane 19 are placed.

The polymer film 19 on which the bicells are placed is passed through a roller laminator so that the bicells are bonded on and under the polymer film 19 .

The double cell 23 bonded at the first point is folded into a Z shape. After the folding is complete, the remaining separator 19 is wrapped around the outside of the stacked bicell and tightly fixed and protected with adhesive tape 27 .

(preparation of battery)

The stacked two-cell batteries prepared as above were placed in aluminum foil packaging. A liquid electrolyte comprising 1M _LiPF6 in EC/EMC (1:2 by weight) solution was then injected and packaged.

(evaluate)

The evaluation results of the cycle characteristics of the storage battery using charge and discharge tests are shown in FIG. 11 . Reference numeral 105 shows the cycle characteristics of the prepared storage battery, wherein at the first and second times, the charge and discharge capacity was 0.2C, and then from the third time, charge 0.5C/discharge 1C, and from this time, the result The graph is shown on the curve.

The electrochemical element of the present invention using a full battery or a double battery as a multilayer stack of unit cells is easy to manufacture, has a structure that can effectively utilize the available space, and can particularly maximize the content of active electrode materials, thereby enabling a high degree of integration battery.

Claims (24)

1. A kind of electrochemical element, comprises the electrochemical cell of multilayer stacking, and described electrochemical cell is to have negative electrode successively as basic unit by stacking, separating layer, and the full cell of anode, and the full battery placed in each stacking Formed as a separator between batteries, where: The separator has a unit length capable of enveloping the electrochemical cell and is folded outwards each unit length starting from the electrochemical cell at a first point to fold each electrochemical cell in a Z-shape, continuously until the last point electrochemical cells, while the remaining separator wraps the exterior of the stacked cells. 2. The electrochemical element according to claim 1, wherein the outermost end of said separator is fixed with an adhesive tape. 3. The electrochemical element according to claim 1, wherein the outermost end of said separator is fixed with heat sealing. 4. The electrochemical element according to claim 1, wherein said separator is selected from the group consisting of microporous polyethylene films, microporous polypropylene films, multilayer films prepared in combination thereof, and polymer films used as polymer electrolytes, The polymer includes polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride-hexafluoropropylene copolymer. 5. The electrochemical element according to claim 1, wherein said separator is a polymer film used as a polymer electrolyte, said polymer film comprising a first microporous polymer layer and polyvinylidene fluoride- A second gel polymer layer of chlorotrifluoroethylene copolymer, wherein said first microporous polymer layer is selected from microporous polyethylene films, microporous polypropylene films, or multilayer films prepared from combinations thereof . 6. The electrochemical element according to claim 1, wherein each cathode of said full cell is an electrode with cathode material coated on both sides of the cathode current collector, and said each anode is an electrode with anode material coated on both sides of the anode current collector electrode. 7. The electrochemical element according to claim 1, wherein each full cell placed on the outermost side of the electrochemical cell comprises a cathode material coated on one side of the cathode current collector, or an anode material coated on one side of the anode current collector The anode on one side of the appliance, and the collector foil is placed on the outermost side. 8. A method for preparing an electrochemical element comprising an electrochemical cell stacked in multiple layers and housed in a storage battery case, the electrochemical cell is sequentially provided with a cathode, a separator, and a stack as a basic unit The full cell of the anode, and the separator placed between each stacked full cell, the separator has a unit length capable of wrapping the electrochemical cell, and is folded outwards from the electrochemical cell at the first point Each unit length, to fold each electrochemical cell in a Z shape, continuously until the last point of the electrochemical cell, while the remaining separator wraps the outside of the stacked cells, the method comprising the following steps: a) Continuously or alternately place full cells above and below the separator; b) laminating the full cell placed in step a) and the separator; and c) Fold the laminated full cells and the separator of step b) outward toward the full cells immediately adjacent to the first full cell, fold each full cell in a Z shape, and roll up the remaining The separator wraps at least one turn around the outside of the stacked full cells, thereby stacking the full cells. 9. The method according to claim 8, further comprising step d): fixing the ends of the separator with adhesive tape. 10. The method according to claim 8, further comprising the step e) of fixing the ends of the separator with a heat sealing method, the heat sealing being performed by bringing a heat sealer, or a hot plate, into contact with the separator. 11. The method according to claim 8, wherein each full cell in step a) is placed above or below the separator. 12. An electrochemical element, comprising a multilayer stacked electrochemical cell, the electrochemical cell is stacked by i) a bicell having, in sequence, a cathode, a separator, an anode, another separator, and another cathode as the basic unit; or ii) as a basic unit, a bicell having in sequence an anode, a separator, a cathode, another separator, and another anode; and a separator placed between each stacked bicell, wherein: The separator has a unit length capable of enveloping the electrochemical cell and is folded outwards each unit length starting from the electrochemical cell at a first point to fold each electrochemical cell in a Z-shape, continuously until the last point electrochemical cells, while the remaining separator wraps the exterior of the stacked cells. 13. The electrochemical element according to claim 12, wherein the outermost end of said separator is fixed with an adhesive tape. 14. The electrochemical element according to claim 12, wherein the outermost end of said separator is fixed by heat sealing. 15. The electrochemical element according to claim 12, wherein said separator is selected from the group consisting of microporous polyethylene films, microporous polypropylene films, multilayer films prepared by combinations thereof, and polymer films used as polymer electrolytes, The polymer includes polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride-hexafluoropropylene copolymer. 16. The electrochemical element according to claim 12, wherein said separator is a polymer film used as a polymer electrolyte, said polymer film comprising a first microporous polymer layer and polyvinylidene fluoride- A second gel polymer layer of chlorotrifluoroethylene copolymer, wherein said first microporous polymer layer is selected from microporous polyethylene films, microporous polypropylene films, or multilayer films prepared from combinations thereof . 17. The electrochemical element according to claim 12, wherein said electrochemical cell is by alternately stacking i) sequentially having a negative electrode, a separator, an anode, another separator, and a double cell of another negative electrode; and ii) having sequentially An anode, a separator, a cathode, another separator, and another anode form a double cell. 18. The electrochemical element according to claim 12, wherein each cathode of said bicell is an electrode with cathode material coated on both sides of the cathode current collector, and said each anode is an electrode with anode material coated on both sides of the anode current collector. electrode. 19. The electrochemical element according to claim 12, wherein each double cell placed on the outermost side of the electrochemical cell comprises a cathode material coated on one side of the cathode collector, or an anode material coated on the anode collector The anode on one side of the appliance, and the collector foil is placed on the outermost side. 20. A method for preparing an electrochemical element comprising multilayer stacked electrochemical cells by alternately stacking i) sequentially as a basic unit with a cathode, a separator, an anode, another separator, and and ii) a bicell having an anode, a separator, a cathode, another separator, and another anode in sequence as a basic unit; and a separator placed between each stacked bicell and Formed, the separator has a unit length capable of wrapping the electrochemical cell, and starting from the electrochemical cell at the first point, folds each unit length outward to fold each electrochemical cell in a Z-shape, continuously until the end One point of the electrochemical cell, while the remaining separator wraps the outside of the stacked cell, the method comprising the steps of: a) Place the double cells continuously or alternately above and below the separator; b) laminating the double cell placed in step a) and the separator; and c) Fold the laminated bicell and the separator of step b) outward toward the bicell immediately adjacent to the first bicell, fold each bicell in a Z shape, and roll up the remaining The separator wraps at least one turn around the outside of the stacked bi-cells, thereby stacking the bi-cells. 21. The method according to claim 20, further comprising the step d): fixing the ends of the separator with adhesive tape. 22. The method according to claim 20, further comprising the step e) of fixing the ends of the separator with heat sealing, the heat sealing being performed by bringing a heat sealer, or a hot plate, into contact with the separator. 23. The method according to claim 20, wherein said double cells of step a) are placed above or below the separator. 24. The method according to claim 20, wherein said electrochemical cell is a double cell by alternately stacking i) sequentially having a cathode, a separator, an anode, another separator, and another cathode; and ii) having an anode in sequence, A separator, a cathode, another separator, and another anode form a double cell.

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